// 代码改进
setTimeout(function (){
	var a = 'hello'
	setTimeout(function(){
		var b = 'lagou'
		setTimeout(function(){
			var c = 'I ♥ U'
			console.log(a + b + c)
		}, 10)
	},10)
},10)

// 改为异步代码promise
new Promise((resolve, reject) => {
	var a = 'hello'
	resolve(a)
}).then(value => {
	var b = 'lagou'
	return value + b
}).then(value => {
	var c = 'I ♥ U'
	console.log(value + c)
})